This invention relates to an axially centering apparatus used for centering optical fibers to be connected in case of fusion-bonding the optical fibers end to end.
When a pair of optical fibers to be connected are fusion-bonded, the axial centers of the ends of the optical fibers to be connected are accurately brought into coincidence, the ends of the optical fibers to be connected are opposed and fusion-bonded so as to suppress an increase in the transmission loss of the connecting portions of the optical fibers known per se.
In an operation of bringing the axial centers of the optical fibers to be connected, i.e., in an operation of axially centering the ends of the optical fibers to be connected as shown in FIG. 14, coating layers are removed from the end portions of a pair of coated optical fibers F.sub.11 and F.sub.21 to be connected, the bare end portions F.sub.12 and F.sub.22 of the optical fibers are cut and aligned, the end portions F.sub.12 and F.sub.22 of the optical fibers are opposed at a predetermined interval of the end faces of the end portions of the optical fibers, and finely adjusted in X-axis direction and Y-axis direction.
Various types of centering stands used for axially centering the end portions of the optical fibers to be connected have been proposed, and that disclosed in Japanese Patent Laid-open No. 111120/1984 is commonly used at present, and the conventional example will be described with reference to FIGS. 15 to 17.
In a centering stand 100A for finely adjusting in an X-axis direction in FIG. 15, a guide 102A having a long groove 101A for engaging an optical fiber on the upper surface is supported through a fulcrum 104A formed on a flat base 103A, and the center X.sub.1 of the long groove 101A and center X.sub.2 of the fulcrum 104A are aligned on the same vertical line.
In a centering stand 100B for finely adjusting in a Y-axis direction shown in FIG. 16, a guide 102B having a long groove 101B for engaging an optical fiber on the upper surface is supported through a fulcrum 104B formed on the upper inside surface of an angle type base 103B, and the center Y.sub.2 of the long groove 101B and the center Y.sub.2 of the fulcrum 104B are aligned on the same horizontal line.
Both the centering stands 100A and 100B are opposed fixedly to align the long grooves 101A and 101B along a rectilinear line as shown in FIG. 17.
In FIG. 17, when an external force (load) of a direction Fx is applied to the guide 102A, the fulcrum 104A is elastically deformed in the same direction in response to the external force, and the guide 102A is finely moved in the X-axis direction. Thus, the end portion F.sub.12 of the optical fiber engaging in the long groove 101A of the guide 102A is finely adjusted in the X-axis direction.
In FIG. 17, when an external force of a direction Fy is similarly applied to the guide 102B, the fulcrum 104B is elastically deformed in the same direction in response to the external force, and the guide 102B is finely moved in the Y-axis direction. Thus, the end portion F.sub.22 of the optical fiber engaging in the long groove 101B of the guide 102B is finely adjusted in the Y-axis direction.
Thus, the end portions F.sub.12 and F.sub.22 of both the optical fibers are axially centered.
When a load is applied to the centering stand, means shown in FIG. 18 is used in general.
A lateral load imparting mechanism 200 in FIG. 18 includes a motor 203 in which a gear 202 is mounted on a motor shaft 201, a rotational shaft 205 on which a gear 204 engaging with the gear 202 is mounted, a movable block 206 moving forward or reversely in the axial direction of the shaft 205 upon normal or reverse rotating of the shaft 205, a push shaft 207 provided at the end side of the block 206, and a spring 209 mounted on a push shaft 207 between the movable block 206 and a supporting plate 208, and the push shaft 207 disposed at the end side of the movable block 206 is contacted with the guide 102A of the centering stand 100A.
A plurality of projections 210, 211 made of conductors are formed at an axial interval on the outer peripheral surface of the movable block 206, an origin detecting pin 212, and overrun detecting pins 213, 214 are disposed at a predetermined interval in a manner capable of being contacted with the projections 210, 211 and the pins 212, 213, 214 are held through an insulating holder 215.
The intervals of the projections 210, 211, and the pins 212, 213, 214 are set according to an empirical rule, and the interval of the overrun detecting pins 213, 214 corresponds to the moving range of the movable block 206 to be described later.
The projections 210, 211 and the pins 212, 213, 214 respectively become electric contacts, and are electrically connected to a warning mechanism, a displaying mechanism, etc., not shown.
In the load imparting mechanism 200 in FIG. 18, when the motor 203 is rotated normally or reversely, the rotation of the motor 203 is transmitted through the motor shaft 201, and the gears 202, 204 to the rotational shaft 205 to move forward or reversely movable block 206 through the rotational shaft 205. Thus, a load of Fx direction is applied through the push shaft 207 at the end of the movable block to the guide 102A of the centering stand 100A to reduce the load or to erase the load, and the guide 102A is finely moved in a predetermined direction in the amount of the applied load.
In this case, the projections 210, 211 of the movable block 206 are contacted with any of the origin detecting pin 213 or the overrun detecting pins 214 to notify and display the finely moving state of the guide 102A by the warning mechanism, the displaying mechanism electrically connected to them. Thus, the guide 102A is avoided to be displaced out of the adjusting range to be efficiently adjusted and the original position of the guide 102A is identified.
The centering stand 100 which has been omitted for the description is associated vertically with the load imparting mechanism 200 of FIG. 18, which is used similarly to the above-mentioned operation.
In the above-described conventional axially centering apparatus, the external forces of Fx or Fy direction are applied to the guides 102A, 102B of the centering stands 100A, 100B to be simply finely adjusted in X-axis and Y-axis directions, and the respective adjusting systems are independent from each other. Thus, the high adjusting accuracy is secured.
However, since the constitutions of the centering stands 100A, 100B are different, they are uneconomic due to the necessity of the two types of centering stands.
Further, since the load imparting mechanisms associated with the centering stands 100A, 100B must apply different forces, Fx and Fy, in the x and y directions, the operability is wrong, and since the load imparting mechanisms are bulky elevationally and laterally, the entire apparatus cannot be reduced in size.